Rubber heel



Aug. 9, 1938. c. LAMB 2,126,561

RUBBER HEEL Filed Dec. 20, 1937 III Patented Aug. '9, 1938 UNITED STATESPATENT OFFICE RUBBER. HEEL Charles Lamb, South Pasadena, Calif.Application December 20, 1937,. Serial No. 180,678

2 Claims. Cl. 36-35) This invention relates to the orthopedic art andparticularly to heels made of rubber or other elastic material.

Extensive experimentation has been carried on 5 from time to time withthe object of providing a rubber heel which when used will tend tocorrect or mitigate the condition of fallen arches commonly known asflat feet. While engaged for many years in the manufacture of ortholpedic rubber heels, I have made an intensive study of this problem, andhave noted that one of the main differences of all these so-calledorthopedic corrective rubber heels has been, first,

that they did not supply a suflicient degree of 15 resiliency in themain body of the heel and, secondly, that they were subject to arelatively rapid wearing down oi the rear outer corners of the heels.The low degree oi resiliency present in the main body of most of theseheels had a tend- 20 ency to defeat whatever advantage there is in arubber heel in the way of correcting a tendency towards fallen arches orin relieving such a condition after it has become acute. I also notedthat the rapid wearing down of the rear 25 outer corners of rubber heelsgenerally resulted in. rendering these practically valueless after arelatively short period of use in so far as any corrective tendency theymight have. This is because of the fact that whenso worn down the 30fulcrum point in the heel moves forwardly so that instead of causing theshoe to pull down and rearwwdiy the metatarsals of the foot, so that theconstrictive action of the tendons under the foot would hit the internalcuniform and sca- 35 phoid structure of the instep upwardly,-the shoewould tend in fact to resist the forward turning moveiuent about thefulcrum in the heel and the tendency would be for the weight of the bodyto m thrown downwardly on the instep struclo ture with the ultimateresult of straining this.

Beginning with the observation of these facts, l proceeded through myexperiments to the discovery that a new rubber heel having adequateresiliency in the main body thereof produces a 4.5 distinctly beneficialedeet resulting from corrective iorces applied to the arch structure ofthe loot, tending to produce a high arch. Such a heel continues toproduce this corrective effect moreover so loud as it retains asubstantially flat to lower surface and a substantially uniform degreeoi resiliency from the extreme rear of the heel tothe front thereoi'.

it is, therefore, an object of my invention to provide an orthopedicrubber heel which shall Eli possess a substantially high degree ofresiliency throughout the main body thereof and which will tend, whenused, to maintain over a relatively long period of use a substantiallyflat lower surface.

It is a further object of my invention to provide an orthopedic rubberheel the reaction to use of which is such that this heel will retain asubstantially high degree of resiliency in the rear outer portion of theheel over a relatively long periodo! use.

Yet another object of my invention is to provide an orthopedic rubberheel, the reaction to use of which will be such' as to maintain theoriginal shape of said heel to an extent that the fulcrum about whichthe foot is caused to rock,

as this heel engages the ground, is maintained at a substantiallymaximum distance rearwardly, as when the said heel is new.

A still further object of my'invention is to provide an orthopedicrubber heel having the characteristics above referred to and which isrelatively inexpensive to produce.

The manner of accomplishing the foregoing objects as well as furthervobjects and advantages will be made manifest in the followingdescription taken in connection with the accompanying drawing in which-Fig. 1 is a side elevational view of a man striding and with the shoe ofhis foremost toot poised so that a rubber heel thereon is just about toengage the ground. i

Fig. 2 'is a perspective view of the preferred form of my invention whenembodied in a rubber heel for the right foot.

Fig. ii is a vertical sectional view taken on the line 3-4 of Fig. 2,and which shows the structure of said heel when it is new.

Fig. 4 is a diagrammatic cross-sectional view similar to Fig. 3 andillustrating the condition of said heel after it has been subjected to aconto siderable period of use.

Fig. 5 is a diagrammatic sectional view of an ordinary rubber heel afterit has been subjected to approximately the same amount of wear as theheel of my invention illustrated in Fig. ii.

In searching for a solution to the problems referred to herelnabove, Idiscovered that the abnormal wearing away oi the bottom face of a rubberheel in the area at maximum wear may be greatly decreased by theprovision of material on so the other portions oi the lower face of theheel which would tend to wear away more. rapidly than the material usedin the area oi maximum wear.

As a preferred embodiment 01' my invention, it

relatively high resistance to abrasion. The body of rubber ll forms arelatively thick upper layer in the heel ll of substantially uniformthickness throughout the heel except opposite-the area of maximum wearI: in which the rubber of the body ll extends downwardly to the lowerface of the heel. Opposite the balance of the lower surface of the heeli I have provided a relatively thin inlay II of rubber which is lessresilient than the body of rubber i I, and much more susceptible toabrasion.

g In the manufacture of the heel ill the body II and the inlay it arevulcanized into a single integral entity.

By virtue of the much greater susceptibility of the insert ii toabrasion than the rubber of the main body ll of the heel III, the inserti3 wears away more rapidly in use than that portion of the body iiopposite the area of maximum wear II. This results in the wearing awayof the bottom portion of the heel I 0 when the latter is in use so as tomaintain the bottom of'the heel sub-- stantially flat as shown in Fig.4. The wearing of the bottom surface of the heel in this manner resultsin maintaining a relatively uniform degree of resiliency throughout thelength of the heel for a relatively long period of use.

The advantages of this result are illustrated in the drawing by linesA-A, 3-H and CC in Figs. 3, 4 and 5 respectively, these lines indicatingthe planes of contact between the heel and the ground which determinethe fulcrum of rotation of the heel relative to the ground when the footis planted on the ground and the weight of the body transferred theretoin walking rapidly as shown in Fig. l.

In Fig. 3 it is seen that the plane AA is such that the ball of the footmust be on the ground before the heel contacts the ground on this plane,

thereby assuring that the fulcrum axis bf the heel is disposed veryclose to the rear end of the heel. This fact and the high degree ofresiliency of the heel results in a rotational. force being produced bythe heel tending to force the front portion of the shoe downwardly. Theresistance to this force by the compression and tension couples of thebone and tendon structure of the foot stimulates a downward flexing ofthe metatarsals to bring the ball of the foot down and back and archupward the central structure of the foot including the metatarsals, theinternal cuniforms and the scaphoid bones.

Owing to the uniform wearing of the bottom surface of the heel of myinvention this heel after a considerable period of wear, as shown inFig. 4,

the arch structure of the foot as above outlined.

While I have devised a number of embodiments still retains thebeneficial effects of a new heel on of the heel of my inventionillustrated herein, some of which have a multiplicity of inserts in thebottom of the heel HI and one of which I have disclosed in my co-pendingapplication for U. 8. Letters Patent, Serial No. 180,677 and filedherewith, the present preferred embodiment may be made to substantiallyaccomplish the benefits of the invention and yet is materially cheaperto manufacture than the other forms thereof owing to the fact that onlya single insert I3 is required in the manufacture of the heel. Thisgreatly simplifies the assembly of the molding rubber in the' mold, anda high quality article of this type may thereby be produced at a muchlower cost than where multiple inserts are required.

In Fig. 5 I have illustrated an ordinary rubber heel 20 as it appearsafter a considerable period of use, the line 0-0 indicating the plane ofinitial contact between a rear lower face ll of the heel and the ground.This plane is seen to be such as to throw the fulcrum about which theshoe rotates away forward towards the middle of the heel. This effects atendency to rotate the shoe in exactly the opposite direction as a newheel. In other words the heel 20 after engaging the ground on the planeof line (7-0 not only exerts no corrective force thereafter on the archstructure of the foot, but on the contrary produces a negative reactionapplying undue strains on the arch.

The foregoing comparison can be demonstrated by anyone by alternatelywearing a pair of shoes having new rubber heels and a pair of shoeswhich are badly run down at the outward rear portions thereof andcarefully noting the exact-.

ly opposite reaction obtained.

What I claim is:

1. A heel comprising a body of rubber which includes: a base or upperlayer of relatively high resiliency and abrasion resistance, said baselayer extending down to the lower face of said heel in the area ofmaximum wear; and a lower layer of uniformly and relatively lowresiliency and abrasion resistance, said lower layer covering thebalance of the downwardly disposed areas of the lower face of said heel,said layers being vulcanized into a unitary body.

2. A heel comprising a body of rubber which includes: a relatively thickbase or upper layer of relatively high resiliency and abrasionresistance, said base layer extending down to the lower face of saidheel in the area of maximum wear; and .a relatively thin lower layer ofuniformly and relatively low resiliency and abrasion resistance, saidlower layer covering the balance of the downwardly disposed areas of thelower face of said heel, said layers being vulcanized into a unitarybody.

CHARLES LANIB.

